The present invention relates to optical communications.
Low-density parity check (LDPC) codes are becoming standard codes in many applications due to their outstanding performance in the waterfall region. However, the error floor phenomenon prevents the usage of LDPC in optical transmission systems, because the required bit error rate for the optical transmission system is typically as low as 10−15. As a result, a concatenated BCH and LDPC coding system has been proposed to eliminate the error floor. However, the performance of concatenated LDPC and BCH codes in the waterfall region becomes degraded compared to that of LDPC due to a phenomenon called rate loss.